Such an engine type, as better described in French patent applications No. 2,818,324 and 2,818,325, comprises at least a cylinder, a piston sliding in this cylinder, a combustion chamber delimited on one side by the upper face of the piston comprising a teat arranged in the centre of a concave bowl and at least one injection nozzle for injecting fuel with a nappe angle less than or equal to
      2    ⁢          Arc      ⁢      tg        ⁢          CD              2        ⁢        F              ,where CD is the diameter of the cylinder and F the distance between the point of origin of the fuel jets from the injection nozzle and the position of the piston corresponding to a crank angle of 50° to the top dead centre.
Thus, in case of early injection, i.e. when the position of the piston is in the vicinity of 50° crank angle for the injection phase selected in relation to the piston top dead centre, the fuel does not come into contact with the cylinder wall and it mixes with the air or the mixture of air and of recirculated exhaust gas present in the combustion chamber.
However, in the case of very high loads, for example at 4000 rpm full load, the engine runs in conventional combustion mode. In this combustion mode, and considering the relatively low compression ratio (of the order of 14), the fuel is conventionally injected into the combustion chamber in a single sequence, but it burns only after a certain delay time linked with the interaction of the fuel jets with the piston wall, existing with the type of homogeneous combustion developed by the applicant. This leads to a decrease in performances, notably as regards the developed power.
The present invention aims to overcome the aforementioned drawbacks by means of a method allowing the fuel to be introduced in such a way that the self-ignition delay thereof is reduced.